Punch stripper

ABSTRACT

A punch stripper unit comprising an integral polyurethane body member having a steel band embedded therein which reinforces the body member and threadingly receives locking screws for securing a punch in a punch receiving hole passing through the body member. The polyurethane provides its own spring-back force when compressed during a punching operation to forcibly remove a punch member mounted in the stripper unit from a punched hole. The workpiece engaging surface of the polyurethane body does not mar workpieces being punched since polyurethane is non-abrasive. Further, an oil retaining reservoir in the form of a groove formed around the outside of the stripper unit communicates with the punch receiving hole via lubricating channels for continuously supplying lubricant between the surface of the punch receiving hole and a punch disposed therein. In addition, oil collecting means may be provided for lubricating the walls of the punching end of the punch for facilitating punching of a workpiece.

[4 June 20, 1972,

[54] PUNCH STRIPPER [72] Inventor: Dominick Rienzi, 15 Jefferson St.,Nutley,

22 Filed: Aug. 24, 1970 21 Appl,No.: 66,363

[52] US. Cl ..83/139, 83/169, 83/698 [51] Int. Cl. ..B26d 7/06, B26d7/18 [58] Field ofSearch ..83/139, 169,698

[56] References Cited UNITED STATES PATENTS 2,815,814 12/1957 Taylor ..L83/139 3,269,238 8/1966 Whistler, Sr. et a1. ..83/139 Primary Examiner-Frank T. Yost Attorney+bemen David & Littenber'g 57 ABSTRACT A punchstripper unit comprising an integralpolyurethane body member having asteel band embedded therein which reinforces the body member andthreadingly receives locking screws for securing a punch in a punchreceiving hole passing through the body member. The polyurethaneprovides its own spring-back force when compressed during a-punchingoperation to forcibly remove a punch member mounted in the stripper unitfrom a punched hole. The workpiece engaging surface of the polyurethanebody does not mar workpieces being punched since polyurethane isnon-abrasive; Further, an oil retaining reservoir in the form of agroove formed around the outside of the stripper unit communicates withthe punch receiving hole via lubricating channels for continuouslysupplying lubricant between the surface of the punch receiving hole anda punch disposed therein. In addition, oil collecting means may beprovided for lubricating the walls of the punching end of the punch forfacilitating punching of a workpiece.

15 Claims, 7 Drawing figures 1,822,468 9/1931 Wales 1,510,008 9/1924R17,905 12/1930 Wright ..83/169X 2,867,276 1/1959 Taylor ..83/1393,178,106 4/1965 JoneS,Jr. ..83/169X PATENTEDmzo m2 SHEET 10F 3 27. FIG.1

INVENTOR.

DOM/NICK RIENZI LERNER, DAVID 8 LITTENBERG AT TORNE YS PKTENTEBmzo m23.670.613

' sum 20F 3 INVENTOR.

DOM/NICK RIENZI L ERNER, DAVID a L ITTENBERG ATTORNEYS PATENTEBJum nansum 3 or a;

FIG. 6"

INVENTOR.

E N M E m n R L K a m m N v w m D Q m Y u ATTORNEYS PUNCH STRIPPERBACKGROUND OF THE INVENTION Stripper units for punches and the like areof course quite well known. They are used to provide a positive punchremoving force for forcing a punch out of a hole it has formedimmediately subsequent to the punching operation forming the hole. Inaddition, they may serve to guide a punch in a desired path when mountedin, for example, a punch and dye bushing retainer unit or the like. Thepunch stripper unit may comprise, for example, for mounting of a punchtherein, a punch receiving hole which passes entirely through the punchstripper unit and locking means for retaining the punch in a desiredposition within the punch receiving hole. The locking means may, againby way of example, comprise locking screws.

Known means for generating the punch removal, force for stripping apunch from a workpiece, or vice versa, comprise springs which arecompressed during the punching action and, immediately subsequent to theremoval of the punching force, expand forcing the punch out of the holeit has formed. In place of springs, a portion or portions of thestripper unit may be made of a resilient material, such as polyurethane.Though known stripper units employing springs have provided generallysatisfactory'performance, there are always the problems inherent in suchunits, such as the need to replace broken springs, damage due toloosened shoulder bolts, the need to replace stripper plates, etc.Stripper units comprising resilient portions also have providedgenerally satisfactory performance but suffer from similar problems,except of course for the fact that there are no broken springs. Inaddition, there is always room for improvement in unit performance, unitlife, simplicity of manufacture, and costs.

It is the general object of this invention to provide a stripper unitwhich does not suffer from the above-noted disadvantages. It is afurther general object of this invention to provide such a stripper unitwhich will have improved operating characteristics, such as automaticlubrication and non-abrasiveness, will be simple and relativelyinexpensive to manufacture, and will have a long useful life.

SUMMARY OF THE PRESENT INVENTION preferred that the plastic material beof the type which will not abrade so that highly polished pieces, suchas polished brass, can be punched without scratching or marring thesurface thereof. Polyurethane has been found to be particularlydesirable because of its many desirable characteristics, such as itsdurability, resiliency, imperviousness to heat, cold, oils, 6iC..

According to the present invention, the integral stripper unit asdescribed directly above may be formed with a metal reinforcing bandembedded in the plastic material and provided with threaded holes forreceiving locking screws. Still further, the stripper unit of thisinvention may be provided with a lubrication reservoir communicatingwith a punch receiving hole thereof via lubricant channels forcontinuously supplying lubricant to the space between a punch disposedin the hole and the inner surface of the punch receiving hole. Thelubricant can be for reciprocal movement of the punch relative to thestripper unit and/or for facilitating punching of a hole in a workpiece.In the first instance, the lubricant would be supplied between the punchbody and the stripper unit while in the second instance the lubricantwould be supplied to the punching end of the punch so that the portionengaging the workpiece would be lubricated.

More specifically, according to the present invention, there is provideda punch stripper unit comprising an integral body member made ofsubstantially rigid, resilient plastic material, said body membercomprising a punch receiving portion and a BRIEF DESCRIPTION OF THEDRAWINGS FIG. 1 is a perspective view of a first embodiment of a punchstripper unit in accordance with the present invention;

FIG. 2 is a side elevational cross-sectional view of the punch stripperunit of FIG. 1;

FIG. 3 is a cross-sectional view of a second embodiment of a punchstripper unit in accordance with the present invention taken along thelines 33 of FIG. 4;

FIG. 4 is a plan view of the punch. stripper unit of FIG. 3;

FIG. 5 is a side elevational view of a punch adapted for use with thepunch stripper unit of FIGS. 3 and 4;

FIG. 6 is a cross-sectional view of a third embodiment of a punchstripper unit in accordance with the present invention taken along thelines 6-6 of FIG. 7; and

FIG. 7 is a plan view of the punch stripper unit of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings inwhich like reference numerals refer to similar parts throughout, apresently preferred embodiment of a cylindrical punch stripper unit 10in accordance with the invention is shown in FIGS. 1 and 2. Punchstripper units in accordance with the invention may of course take manydifferent forms, such as square, rectangular, oblong, and irregularform,etc. The unit 10 comprises an integral body member 1 1 made ofsubstantially rigid, resilient plastic materi a]. The presentlypreferred body member 11 is made of polyurethane.

The body member 11 is formed with a substantially circular punchreceiving and retaining hole 12. The unit 10 is also formed with a metalband 13 embedded in the plastic material of the body member 11 andsymmetrically and annularly disposed about punch receiving hole 12. Fourlock screws 14 (only three being shown) are disposed in screwdriver orthe like receiving holes 16 symmetrically positioned about punchreceiving hole 12 to symmetrically grip a punch (not shown) which may bedisposed within the punch receiving hole 12. Number, size andtypes ofscrews and their locations may vary whether placed symmetrically orotherwise.

The unit may be made in any well known manner, such as by molding thebody member 11 with the metal band 13 held machined to its desiredconfiguration. The top of the unit.

where the metal band 13 is may be machined down to the band and theexposed surface of the: band used for the stamping of identifyingindicia thereon. As indicated, other known and acceptable methods ofmanufacture may be employed.

The metal band 13, which in the preferred embodiment is made of steel,has threaded holes 18 which threadingly receive the lock screws 14 thusproviding a secure means for mounting of the lock screws 14. Inaddition, the metal band 13 strengthens the unit 10.

The metal band 13 is embedded in an upper portion 20 of the body member11 which is largerin cross-section than the remainder of the unit 10.The upper portion 20 may be formed, for example, to be matingly andslidingly received in a be deposed with its punching end extending belowthe unit or disposed within the unit itself since upon compression ofthe unit, the punching end would extend below the unit. The punch wouldalso have a clamping end which would extend above the unit 10 and beused for clamping of the assembled punch and unit 10 in a punch retainerunit. During a punching operation, the assembled punch retainer unit,punch stripper unit 10, and punch would be moved towards a workpiececausing the punch to punch a hole in the workpiece at which time thelower or workpiece engaging surface 22 of punch stripper unit 10 engagesthe workpiece surface.

The body member 11 will be compressed during the punching movement. Uponremoval of the punching force, the body member 11 springs back to itsoriginal shape popping the punch out of the punched hole. This iscommonly called stripping in that the workpiece is stripped from thepunch or vice versa.

The integral body member 11 further comprises a reduced diameter portion25, an annularly flanged portion 24, and a bottom portion 27. Theflanged portion 24 has an annular groove 26 formed in its upper surfaceas viewed in the drawings. The groove 26 may serve as a lubricantreservoir, such as an oil reservoir. In this regard, it will be notedthat the outside diameter of the annular portion 24 is approximatelyequal to the outside diameter of the upper portion 20. Thus, if, forexample, oil is disposed in the groove 26 and the stripper unit 10 isretained in a mating cylindrical hole of a punch retaining unit or thelike, the oil in the groove 26 will be retained in the chamber formed bythe wall of the mating cylindrical hole, the lower surface of upperportion 20, the outer surface of reduced diameter portion 25, and theupper surface and groove 26 of flanged portion 24.

Lubricant channels 28 lead from groove 26 to lubricant holes 30 in thesurface 32 of punch receiving hole 12. By means of the groove 26,lubricant channels 28, and lubricant holes 30, lubricant in groove 26will be continuously fed between the surface of a punch disposed withinpunch receiving hole 12 and the hole surface 32.

A second presently preferred embodiment of a punch stripper unit 34 inaccordance with the invention is shown in FIGS. 3 and 4. The unit 34differs from the unit 10 in that there is no bottom portion 27 disposedbelow the annularly flanged portion 24. In addition, and moreimportantly, an annularly inwardly extending portion 36 partially sealsthe bottom of punch receiving hole 12. The lubricating channels 28 leadto a groove 30 formed in the annular portion 36. This leaves a raisedportion 37 extending about a punch end guiding hole 13 defined byannular portion 36.

A punch 39 adapted for use with punch stripper unit 34 is shown in FIG.5. Punch 39 comprises a main body portion 47 having a recessed portion41 formed therein for facilitating movement of punch 39 within a closelyfitting cylindrical cavity, such as the cavity presented by punchreceiving hole 12. Punch 39 further comprises a greatly reduced diameterpunching end 43 which is connected to the main body portion 47 by asmoothly contoured portion 45.

When the punch 39 is disposed within punch receiving hole 12 of unit 34,punch end 43 extends slightly below or above workpiece engaging surface22. During compression of unit 34 upon punching of a workpiece,lubricant in groove 38 is forced out of the groove and into contact withthe contoured portion 45 of punch 39. This occurs during each punchingoperation and thereby repeatedly and thus continuously lubricates thecontoured portion 45 and thereby the punch end 43 during continuouspunching operations to provide improved punch performance. Thus,lubricant is directly and automatically and continuously supplied to thepunching end 43 and contoured portion 45 when utilizing unit 34. It isto be noted in this regard that lubricant also reaches the punching endof a punch when utilizing unit 10 shown in FIGS. 1 and 2 since it willwork its way down the punch due to the force of gravity.

A presently preferred third embodiment of a punch stripper unit 40 inaccordance with the present invention is shown in FIGS. 6 and 7. Unit 40differs from unit 10 in that it is adapted to accommodate five separatepunches in punch receiving holes 12. Further, recesses 50 have beenformed in body member 11 to take up compression and avoid binding of theunit 40 in a punch and dye retaining unit or the like during a punchingoperation. It will be appreciated in this regard that the material, suchas polyurethane, of the body 11 expands outward during axialcompression. This outward expansion is accommodated in all of the unitsby the reduced diameter portion 25. In the multi-prone unit 40, therecesses 50 are additionally provided to aid in preventing distortion ofany of the plurality of punch receiving holes 12.

The smaller four holes 12 surrounding the larger hole 12 comprisecounterbored portions 44 and 46 which leave an annular portion 48defining a punch guiding surface 42. The counterbored portions 44 and 46are provided to take up compression and avoid binding of a punchdisposed within their respective holes 12.

Lubricating channels 28 leadfrom a common groove 26 to all of punchreceiving holes 12. However, lock screws 14 are only provided forcooperation with a punch disposed within the larger central punchreceiving hole 12. Mounting of the unit 40 on a punch disposed in thelarger central punch receiving hole 12 would automatically align theremaining four punches in the remaining smaller holes 12.

Punch stripper units made in accordance with the present invention havebeen found to possess many advantages over present stripper units. Forexample, they have much longer useful lives (up to two times longer thanthe best known present stripper units); they can be used to strip variedmetal thicknesses; they provide greater compression travel than possiblewith present stripper units; they are extremely safe (they are lightweight and have no sharp edges); they greatly reduce punch noise; theydo not mar workpiece surfaces, and they can withstand rough handlingwithout damage.

The present description has been by way of example and is not intended,in any way, as a limitation to the scope of the invention as defined inthe appended claims. For example, it may be that a punch stripper unitin accordance with the present invention may be made of a plasticmaterial having properties which will obviate the need for a metal bandmember. Similarly many different shapes of the unit 10 and oil reservoir26 are possible within the spirit and scope of the invention.

I claim as my invention:

1. A punch stripper unit comprising an integral body member made ofsubstantially rigid, resilient plastic material, said body membercomprising a punch receiving portion and a work piece engaging portion,means for retaining a punch in said punch receiving portion, said punchretaining means comprising lock screws and metal means for threadinglyreceiving said lock screws.

2. A unit according to claim 1, wherein said metal means comprises ametal band embedded in the plastic material of said body member.

3. A unit according to claim 2, wherein said metal band is made ofsteel.

4. A unit according to claim 3, wherein said punch receiving portion ofsaid body member comprises a substantially circular hole formedtherethrough, and said metal band is symmetrically disposed within saidbody member about said hole.

5. A punch stripper unit comprising an integral body member made ofsubstantially rigid, resilient plastic material, said body membercomprising a punch receiving portion and a work piece engaging portion,means for retaining a punch in said punch receiving portion, said punchreceiving portion comprising a punch receiving hole passing through saidbody member, and said body member further comprising lubricant storagemeans for storing lubricant and continuously supplying it to theinnersurface defined by said punch receiving hole.

6. A unit according to claim 5, wherein said lubricant storage meanscomprises a groove formed in said integral body member and lubricantchannels leading from said groove to lubricating holes formed in theinner surface defined by said punch receiving hole.

7. A unit according to claim 6, wherein said punch receiving hole issubstantially circular in cross-section, said body member comprises anupper portion which is substantially annular in cross-section, a reducedouter diameter annular middle portion adjacent said upper portion, and alower flangelike annular portion adjacent said middle section and havingan outer diameter substantially equal to the outer diameter of saidupper portion, and said groove is formed in the upper sur face of saidflange-like portion.

8. A unit according to claim 7, wherein said lubricating channelscomprise channels leading downwardly from said groove to saidlubricating holes.

9. A unit according to claim 6, wherein said body member comprises anupper portion; a middle portion adjacent said upper portion and having areduced outer periphery in relation to said upper portion, and a lowerportion adjacent said middle portion and having an outer peripherysubstantially congruent with that of said upper portion, and said grooveis formed in the upper surface of said lower portion which surface isdefined by the differences between the outer peripheries of the middleand lower portions.

10. A unit according to claim 9, wherein said plastic material ispolyurethane, said punch retaining means comprises lock screws and ametal band embedded in said plastic material and threadingly receivingsaid lock screws, said metal band being disposed about said punchreceiving hole, and said workpiece engaging portion comprises a bottomportion disposed adjacent said lower portion which bottom portioncomprises a flat lower workpiece engaging surface.

11. A unit according to claim 5, wherein said lubricant storage meansfurther comprises means for supplying lubricant to the punching end of apunch disposed within said punch receiving hole.

12. A unit according to claim 11, wherein said means for supplyinglubricant to said punching end of a punch comprises an integral inwardlyextending portion of said body member which partially closes off thepunching end receiving end of said punch receiving hole, said integralinwardly extending portion defining a punch end guiding hole.

13. A unit according to claim 12, wherein said integral inwardlyextending portion further comprises a recess for retaining lubricant andsaid inwardly extending portion is adapted to cooperate with said recessto supply lubricant to said punch end guiding hole during axialcompression of the said punch stripper unit.

14. A punch stripper unit comprising a punch receiving portion defininga punch hole, a work piece engaging portion, means for retaining a punchin said punch receiving hole, lubricant storage means for storinglubricant and continuously supply it to said punch receiving hole, saidlubricant storage means comprising a groove formed in said punchreceiving portion and lubricant channels leading from said groove tosaid punch receiving hole. r

15. A unit according to claim 14, wherein said groove is formed in anupper surface of said punch receiving portion.

1. A punch stripper unit comprising an integral body member made ofsubstantially rigid, resilient plastic material, said body membercomprising a punch receiving portion and a work piece engaging portion,means for retaining a punch in said punch receiving portion, said punchretaining means comprising lock screws and metal means for threadinglyreceiving said lock screws.
 2. A unit according to claim 1, wherein saidmetal means comprises a metal band embedded in the plastic material ofsaid body member.
 3. A unit according to claim 2, wherein said metalband is made of steel.
 4. A unit according to claim 3, wherein saidpunch receiving portion of said body member comprises a substantiallycircular hole formed therethrough, and said metal band is symmetricallydisposed within said body member about said hole.
 5. A punch stripperunit comprising an integral body member made of substantially rigid,resilient plastic material, said body member comprising a punchreceiving portion and a work piece engaging portion, means for retaininga punch in said punch receiving portion, said punch receiving portioncomprising a punch receiving hole passing through said body member, andsaid body member further comprising lubricant storage means for storinglubricant and continuously supplying it to the innersurface defined bysaid punch receiving hole.
 6. A unit according to claim 5, wherein saidlubricant storage means comprises a groove formed in said integral bodymember and lubricant channels leading from said groove to lubricatingholes formed in the inner surface defined by said punch receiving hole.7. A unit according to claim 6, wherein said punch receiving hole issubstantially circular in cross-section, said body member comprises anupper portion which is substantially annular in cross-section, a reducedouter diameter annular middle portion adjacent said upper portion, and alower flange-like annular portion adjacent said middle section andhaving an outer diameter substantially equal to the outer diameter ofsaid upper portion, and said groove is formed in the upper surface ofsaid flange-like portion.
 8. A unit according to claim 7, wherein saidlubricating channels comprise channels leading downwardly from saidgroove to said lubricating holes.
 9. A unit according to claim 6,wherein said body member comprises an upper portion, a middle portionadjacent said upper portion and having a reduced outer periphery inrelation to said upper portion, and a lower portion adjacent said middleportion and having an outer periphery substantially congruent with thatof said upper portion, and said groove is formed in the upper surface ofsaid lower portion which surface is defined by the differences betweenthe outer peripheries of the middle and lower portions.
 10. A unitaccording to claim 9, wherein said plastic material is polyurethane,said punch retaining means comprises lock screws and a metal bandembedded in said plastic material and threadingly receiving said lockscrews, said metal band being disposed about said punch receiving hole,and said workpiece engaging portion comprises a bottom portion disposedadjacent said lower portion which bottom portion comprises a flat lowerworkpiece engaging surface.
 11. A unit according to claim 5, whereinsaid lubricant storage means further comprises means for supplyinglubricant to the punching end of a punch disposed within said punchreceiving hole.
 12. A unit according to claim 11, wherein said means forsupplying lubricant to said punching end of a punch comprises anintegral inwardly extending portion of said body member which partialLycloses off the punching end receiving end of said punch receiving hole,said integral inwardly extending portion defining a punch end guidinghole.
 13. A unit according to claim 12, wherein said integral inwardlyextending portion further comprises a recess for retaining lubricant andsaid inwardly extending portion is adapted to cooperate with said recessto supply lubricant to said punch end guiding hole during axialcompression of the said punch stripper unit.
 14. A punch stripper unitcomprising a punch receiving portion defining a punch hole, a work pieceengaging portion, means for retaining a punch in said punch receivinghole, lubricant storage means for storing lubricant and continuouslysupply it to said punch receiving hole, said lubricant storage meanscomprising a groove formed in said punch receiving portion and lubricantchannels leading from said groove to said punch receiving hole.
 15. Aunit according to claim 14, wherein said groove is formed in an uppersurface of said punch receiving portion.